All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
It is permissible for a Muslim to manage the finances of a non-Muslim whether the latter is alive or dead, but in case he is dead; his money becomes the right of his heirs who have the same religion like him as we clarified in Fatwa 82785.
However, one should abide by the Sharee’ah rulings in administering this money, so one is not permitted to use it to deal in Riba (interest and/or usury), or sell or buy what is unlawful, like pork, intoxicants and so forth. For more benefit, please refer to Fatwa 86247.
Allaah Knows best.